There is conventionally known a power steering device with an automatic steering function as disclosed in e.g. Patent Document 1.
This power steering device is configured as a rack-and-pinion type hydraulic power steering device including an input shaft coupled to a steering wheel, an output shaft relatively rotatably coupled to the input shaft through a torsion bar, a rotary valve arranged at a position between the input shall and the output shaft on the outer circumference of a base end portion of the input shaft and a hollow motor arranged on the outer circumference of a front end portion of the input shaft.
In such a configuration, the rotary valve is opened in response to a driver's steering torque so as to generate a steering assist torque during normal operation mode. During automatic operation mode, by contrast, the rotary valve is opened by the application of a drive torque of the hollow motor under the control of an ECU so as to generate a steering assist torque for automatic steering operation.